Experimental and numerical studies on the receiving gain enhancement modulated by a sub-wavelength plasma layer

A novel technique based on sub-wavelength plasma structure effects on enhancement of RF communication signals on a receiving antenna is carried out in this paper in laboratory experiments and analyzed by corresponding numerical simulations.Considerable intensification on receiving signal gain up to -10 d B in comparison with that without the plasma modulation is observed experimentally in -1 GHz RF band,with an effective enhancement bandwidth of -340 MHz and the fractional bandwidth of -34%.Then,the optimal modulation parameters of plasma are further studied by a numerical simulation.It is shown that the number density,the layer thickness,and the collision frequency of the plasma,as well as the relative distance between the plasma layer and antenna synergistically affect the modulation.Compared to the metallic antenna with the same overall dimension,the modulated antenna covered by the subwavelength plasma structure features higher receiving efficiency and lower radar cross section in the studied RF band.The mechanism of the reception enhancement is further revealed by analyzing characteristics of electromagnetic scattering and electric field distribution in the subwavelength plasma layer.The results then exhibit scientific significance and application potential of sub-wavelength plasma modulation on compact receiving antennas with higher performance and better feature of radar stealth.

Gain-enhanced reconfigurable radiation array with mechanically driven system and directive elements

In the artificial intelligence-driven modern wireless communication system,antennas are required to be reconfigurable in terms of size according to changing application scenarios.However,conventional antennas with constant phase distributions cannot achieve enhanced gains in different reconfigurable sizes.In this paper,we propose a mechanically reconfigurable radiation array(RRA)based on miniaturized elements and a mechanically reconfigurable system to obtain gain-enhanced antennas in compact and deployed states.A five-element RRA with a phase-reconfigurable center element is designed and analyzed theoretically.The experimental sample has been fabricated,driven by a deployable frame with only one degree of freedom to realize the size and phase distribution reconfiguration simultaneously to validate the enhanced gains of RRA.The proposed RRA can be tessellated into larger arrays to achieve higher gains in other frequency regimes,such as terahertz or photonics applications with nanometer fabrication technology.

The Impact of Substrate Materials to the Design of UWB Modern Antennas

The theory of microstrip antennas has motivated us to design a highly improved gain antenna under this category. It is a microstrip monopole antenna characterized by omni-directional radiation as well as a high radiation gain. A review of different methodologies to designing antennas with broad/ultra-wide band performance for various applications is enriched by our original antenna design. This is an original model analyzed over different substrate materials and finally optimized for the bandwidth of (3.3 - 5.8) GHz just below ?10 dB of return loss (RL). The antenna is judged for high gain when the ground plane size is reduced to nearly half that of substrate. The impact of the substrate materials is discussed in this article. The master design tool is Ansoft High Frequency Simulator Structure (HFSS), one of Finite Element Method (FEM) based software tools. The antenna would be printed on a 1.524 mm thick Rogers (RO3003C) substrate;overall size of 33.4 × 33.4 squared millimeters. At the optimal resonance frequency of 3.8 GHz, simulation results perfectly agree with the standards of UWB antennas, with a high radiation gain and impedance matching status.

Detection of Gain Enhancement in Laser-Induced Fluorescence of Rhodamine B Lasing Dye by Silicon Dioxide Nanostructures-Coated Cavity

In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current （DC） reactive magnetron sputterin technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10-5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.